1. Field of the Invention
This invention relates in general to pattern recognition and in particular to a method and a system for noncontact reading of product or part identification patterns, and more specifically to reading of patterns which are present in relief form.
2. Description of the Prior Art.
The use of bar codes for identification of parts and products is widespread. The most common means of including a bar code for an object is to either affix a printed label, or to print-the code directly on the part or product. Most conventional bar code scanners require very high contrast between the bars and the background in order to properly read the code. In some cases, however, affixing a label or painting a code is either impractical or too expensive. For example, some surfaces will not allow labels to adhere properly or the presence of a label may interfere with the proper operation of the part.
One way to overcome the limitations of bar code labels and painted bar codes is to have the code set in relief on the surface of the object. This can be done by stamping, engraving, etching, milling, molding, or by other methods. The codes can be raised from the surface or can be depressed from the surface. The primary problem with such relief bar codes is that they cannot be read by currently available non-contact scanning techniques, since the contrast between the high and low parts of the pattern is generally very low.